Plasma processing apparatus of substrate and plasma processing method thereof
A substrate plasma processing apparatus includes a chamber of which an interior is evacuated under a predetermined vacuum condition; an RF electrode which is disposed in the chamber and configured so as to hold a substrate to be processed on a main surface thereof; an opposing electrode which is disposed opposite to the RF electrode in the chamber; an RF voltage applying device for applying an RF voltage with a predetermined frequency to the RF electrode; and a pulsed voltage applying device for applying a pulsed voltage to the RF electrode so as to be superimposed with the RF voltage and which includes a controller for controlling a timing in application of the pulsed voltage and defining a pause period of the pulsed voltage.
1. A method for plasma-processing a substrate, comprising:
holding said substrate on a main surface of an RF electrode, said RF electrode being disposed opposite to an opposing electrode in a chamber, an interior of said chamber being evacuated under a predetermined vacuum condition;
applying an RF voltage with a predetermined frequency only to said RF electrode such that said RF electrode is self-biased negatively;
applying a pulsed voltage to said RF electrode such that said pulsed voltage is superimposed with said RF voltage; and
controlling a timing of applying said pulsed voltage and defining a pause period of said pulsed voltage; and
controlling a pulse width t 1 (s) so that the relation of t 1 <((∈ 0 ×∈ s )/(Z×e×Ni×vb))×(Vmax/d) is satisfied (herein, ∈ 0 : vacuum dielectric constant, ∈ s : relative dielectric constant of trench bottom under processing, Z: ionic valency number, Ni: ion density (/m 3 ), vb: Bohm velocity represented by the equation of (k×Te)/Mi, d: thickness of bottom dielectric material, Vmax/d: dielectric withstand electric field strength, Te: electron temperature (eV)).
2. The method as set forth in claim 1 ,
wherein said pulsed voltage is set to a negative pulsed voltage.
3. The method as set forth in claim 1 , further comprising:
setting a frequency ωrf/2π of said RF voltage to 50 MHz or over; and
controlling at least a pulse width t 1 (s) and a voltage value V pulse of said pulsed voltage so that the relation of t 1 ≧(2π/(ωp/5)) is satisfied (herein, ωp is a plasma ion frequency and represented as ωp=(e 2 N 0 /∈ 0 /∈ 0 Mi) 1/2 ; e: elementary charge, ∈ 0 : vacuum dielectric constant, Mi: ion mass (kg), N 0 : plasma density (/m 3 )), and the relation of |V p-p |<|V pulse | is satisfied (herein, V p-p is a voltage value of the RF voltage),
wherein a higher energy side peak of ions incident onto said substrate is adjusted within an energy range for an intended substrate processing.
4. The method as set forth in claim 1 , further comprising:
setting a frequency ωrf/2π of said RF voltage, which is applied to said RF electrode from a pulsed voltage applying device, to 50 MHz or over; and
controlling at least a pulse width t 1 (s) and a period t 2 (s) of said pulsed voltage so that the relation of (2π/ωr×f)<t 1 <t 2 <(2π/(ωp/5)) is satisfied (herein, ωp is a plasma ion frequency and represented as ωp=(e 2 ×N 0 /∈ 0 ×Mi) 1/2 ; e: elementary charge, ∈ 0 : vacuum dielectric constant, Mi: ion mass (kg), N 0 : plasma density (/m 3 )),
wherein an average ion energy of ions incident onto said substrate is adjusted within an energy range for an intended substrate processing.
5. The method as set forth in claim 1 , further comprising:
controlling a pulse number n 1 in a continuous application of said pulsed voltage so that the relation of n 1 <∈ 0 ×∈ s /(Z×e×Ni×vb×t 1 )×(Vmax/d) is satisfied (herein, ∈ 0 : vacuum dielectric constant, ∈ s : relative dielectric constant of trench bottom under processing, Z: ionic valency number, Ni: ion density (/m 3 ), vb: Bohm velocity represented by the equation of k×Te/Mi, t 1 : application period of pulsed voltage, that is, pulse width, d: thickness of bottom dielectric material, Vmax/d: dielectric withstand electric field strength, Te: electron temperature (eV)).
6. The method as set forth in claim 1 , further comprising:
controlling a pause period t 3 (s) so that the relation of n 1 ×t 1 ≦t 3 is satisfied (herein, n 1 : pulse number in continuous application of pulsed voltage, t 1 : application period of pulsed voltage, that is, pulse width).
7. The method as set forth in claim 1 , further comprising:
detecting an etching end or a change of the substrate so that at least one of said pulse width t 1 (s), a pause period t 3 (s) and a voltage value V pulse in said pulsed voltage can be adjusted referring to the thus obtained detecting information.
8. The method as set forth in claim 1 ,
wherein said pulsed voltage is constituted of a plurality of pulsed voltages which are superimposed with one another by shifting the corresponding phases.
9. A method for plasma-processing a substrate, comprising:
holding said substrate on a main surface of an RF electrode, said RF electrode being disposed opposite to an opposing electrode in a chamber, an interior of said chamber being evacuated under a predetermined vacuum condition;
applying an RF voltage with a predetermined frequency only to said RF electrode such that said RF electrode is self-biased negatively;
applying a pulsed voltage to said RF electrode such that said pulsed voltage is superimposed with said RF voltage; and
controlling a timing of applying said pulsed voltage and defining a pause period of said pulsed voltage; and
controlling a voltage value V pulse of said pulsed voltage so that the relation of (V therm /V dc ) 1/2 ≦0.5L 1 /L 2 is satisfied (herein, V therm : thermal velocity of ion represented by the equation of (8k×Te/πMi)/2, Vdc=(2e×Z×V pulse /Mi) 1/2 , L 1 : width of trench to be formed, L 2 : depth of trench to be formed, Te: electron temperature (eV)).